In its ongoing battle against software patents, the Free Software Foundation (FSF) has launched PlayOGG.org, a campaign to promote the use of the OGG Vorbis standard for compressed audio. The patent-free and licence-free standard is being punted as an ethically, legally and technically superior audio alternative to the proprietary MP3 format. The most common music format is currently MP3, but what most people don’t realise is that any time a distributor sells or gives away music encoded as an MP3, they are responsible for paying a fee to the owners of the MP3 patents. Any software that runs MP3s is also affected by this. The OGG Vorbis specification, being in the public domain, is free from such restrictions and anyone can use the format or write software to use it without needing permission from a patent holder.

Source: FSF launch playOGG.org